Julius-Kühn-Archiv (Mar 2012)
Impact of multiple resistance mechanisms in black-grass (Alopecurus myosuroides Huds.) populations on the activity of cereal herbicides
Abstract
Herbicide resistance to different modes of action is spreading not only in the intensive winter wheat producing areas of Northern Germany, but also in other regions. In this investigation, four selected biotypes of black-grass (Alopecurus myosuroides Huds.) from Lower Saxony, Schleswig-Holstein and Baden-Württemberg were tested for resistance to different herbicides in greenhouse monitoring trials. Using the Pyrosequencing™ technology, leaf material of the different biotypes was screened for ACCase and ALS target-site mutations. The resistance mechanism profiles of the tested biotypes were first completed with metabolism studies of selected herbicides. Finally, the effectiveness of different ACCase and ALS herbicides was investigated in dose response studies under controlled conditions. The results of the analysis showed the occurrence of multiple resistance mechanisms – target-site and non-target site – in the different black-grass biotypes. The calculated resistance factors for the herbicides varied between biotypes and occurring resistance mechanisms. Independent of the range of the resistance factors, low levels already caused decreased effectiveness under real field conditions. Despite confirmed target-site and enhanced metabolic resistances, most of the tested herbicide mixtures and sequence applications provided useful efficacy levels. Soil-acting herbicides have become the backbone for controlling heavy infestations of black-grass populations in practice. Especially flufenacet and its mixtures provide high efficacy levels for the reduction of the first grass weed flush. Within the herbicide strategy study, Atlantis WG® appeared as the most effective post emergence applied product, especially on biotypes with metabolic resistances. With regard to missing alternative solutions in the near future, a mid to long-term sustainable crop-production can only be assured with mixtures and sequence applications of different herbicides and modes of action combined with integrated weed management tools.
Keywords
